I think that the eight Dem candidates who jumped on Dean's pledge to try to earn the votes of white Southerners with confederate flag decals on their trucks lost more credibility than Dean did.
Dean is right: Dems need lower-income whites with a cultural attachment to Dixie. Not because we need to win the South (winning Ohio and the Southwest will make up for it), but because these folks should be voting for Democrats.
Congressman Jackson, Jr. makes the point very well in a Nation article published on his own website here.
It's a good read.